As described above, the one which makes the all edges and corners of the screen darker than the middle of the screen.What vignette effect are you referring to ?
I know that it is part of the "vintage movie look" which the designers are going for, which might be OK during the cut-scenes etc, but during actual gameplay we want to see the whole screen in equal brightness without it going dark at at edges and corners.
Players might start thinking they have an eye condition such as tunnel vision, glaucoma or Retinitis pigmentosa.
It is very unpleasant.